1. Field of the Invention
The present invention relates to an image sensing apparatus that senses still images and moving images and can store, communicate, record and playback the sensed images, and a control method for the image sensing apparatus.
2. Description of the Related Art
Conventionally, an image sensing apparatus such as an electronic camera, which uses a memory card having solid-state memory elements as a recording medium and records and plays back still images and moving images, is already available commercially. Furthermore, a portable printer that prints images and an image processing apparatus such as a personal computer that communicates/stores audio data and video data are also available commercially.
By making portable an image sensing system composed of such electronic cameras and printers, and/or personal computers, it has become possible to work expeditiously outdoors, without being limited to indoor environments such as a home or an office.
In particular, the electronic camera and printer and/or personal computer can be made to work together, to transfer image data sensed using an electronic camera provided with a communication function to a printer provided with a communication function for printing, transfer to a personal computer provided with a communication function using wireless communication, and the like. Conversely, the electronic camera and the personal computer can also be made to work together by being provided with the function to control the electronic camera remotely from the personal computer and sense images or the like, so that it is possible to build a very convenient image sensing system.
In addition, some image sensing apparatuses such as electronic cameras are provided with an auto power off function or similar power saving function, in that power for the electronic camera is automatically turned off after a predetermined period of time has elapsed and the camera has not been operated, the display on a display unit is cut off, and so forth. This function makes it possible to extend the battery drive time of an image sensing apparatus such as the electronic camera.
However, this type of conventional image sensing system composed of an electronic camera and printer and/or personal computer has the following problems. Specifically, when transferring image data sensed with an electronic camera to a printer, if the electronic camera is not operated for a predetermined period of time, the auto power off or other such power saving function operates, which, in turn, interrupts the transfer process during even those operations in which the transfer process should not be stopped.
By contrast, turning off the auto power off or other such power saving function does prevent stoppage of the transfer process due to the power saving function. However, because the power saving function is not executed even during those operations in which the power saving function should be executed and power saved, it is not possible to extend the battery drive time of the electronic camera.
It is also possible to disable the power saving function when transferring image data and then turn the power saving function back on after transfer ends. However, because the power saving function must be turned off and then turned back on every time image data is transferred, operation of the system is inconvenient, and furthermore, one might forget to turn off the power saving function or to turn the power saving function back on, or forget whether the auto power off is currently turned on or turned off.
In addition, when transferring image data between the electronic camera and the printer, the communication link is sometimes broken due to a poor radio environment. In this case, not only can the image data not be transferred, but because the power saving function is not executed until a predetermined period of time elapses, the electronic camera battery is wasted.
In addition, when transferring image data between the electronic camera and the printer, if the radio environment happens to be poor the data transfer rate is decreased when communication is carried out. At this time, since the image data transfer time is lengthened, sometimes the auto power off or other such power saving function operates even when transfer has not ended, and in such cases, the transfer process is cut off even during the transfer process which should not be stopped.